Natural weak value amplification in Fano resonance and giant Faraday rotation in magneto-plasmonic crystal

Shyamal Guchhait,Athira B S,Anwesha Panda,Jeeban Kumar Nayak,Niladri Modak,Nirmalya Ghosh,Mandira Pal

doi:10.1038/s41598-020-68126-8

Shyamal Guchhait, Athira B S + Show 5 more

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https://doi.org/10.1038/s41598-020-68126-8

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Abstract

The extraordinary concept of weak value amplification can be formulated within the realm of wave interference as nearly destructive interference between the eigenstates of the measuring observable. Here we report on a phenomenon of interferometric weak value amplification of small polarization rotation in Fano resonance that evolves completely naturally due to near destructive spectral domain interference between a continuum and a narrow resonance mode having slightly different polarization response. In order to elucidate this, we first experimentally demonstrate an interferometric weak value amplification concept by generating nearly destructive interference of two paths of an interferometer having slightly rotated linear polarization states of light. The weak value amplification of polarization rotation effect is manifested as dramatic changes in the polarization state of light, which acts as the pointer. We go on to demonstrate that the manifestation of natural interferometric weak value amplification is an important contributing factor to the observed giant Faraday rotation and ellipticity in waveguided magneto-plasmonic crystals exhibiting prominent Fano resonance. The natural weak value interpretation of the enhanced Faraday rotation in hybrid magneto-plasmonic systems enriches the existing understanding on its origin. This opens up a new paradigm of natural weak measurement for gaining fundamental insights and ensuing practical applications on various weak interaction effects in rich variety of wave phenomena that originate from fine interference effects.

Highlights

The extraordinary concept of weak value amplification can be formulated within the realm of wave interference as nearly destructive interference between the eigenstates of the measuring observable
Using a theoretical model of interferometric weak value amplification and by employing finite element method (FEM) s imulation[33] in magneto-plasmonic crystal, we demonstrate that natural interferometric WVA plays an important role in the observed giant Faraday rotation in such systems that exhibit prominent Fano resonance features[28]
It is convenient to represent the corresponding changes in the polarization state of light using the intensity-based Stokes v ectorelements[32].Using the weak interaction limit (α → 0) it can be shown that the real and the imaginary WVAs of small polarization rotation effect α are manifested as ǫ

Summary

Introduction

The extraordinary concept of weak value amplification can be formulated within the realm of wave interference as nearly destructive interference between the eigenstates of the measuring observable. Using a theoretical model of interferometric weak value amplification and by employing finite element method (FEM) s imulation[33] in magneto-plasmonic crystal, we demonstrate that natural interferometric WVA plays an important role in the observed giant Faraday rotation in such systems that exhibit prominent Fano resonance features[28]. This is the first demonstration of weak value amplification that occurs completely naturally

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